Our research is focused on the molecular mechanisms which control virus assembly. More specifically, we are studying the morphogenesis of the complex virus, bacteriophage T4, as a model system. We have discovered and mapped a new type of T4 mutant, T4go24-, which promotes viral production in the absence of the protein encoded by gene 24 of T4. The T4go24- mutation is in gene 23, the gene that encodes the major virion capsid protein. The affect of the T4go24- imitation appears to involve a conformational change in protein 23 that permits capsid proteins to be cleaved and complete virions to be assembled without protein 24. We shall compare by protein 23 encoded by normal T4 and T4go24- mutans by tryptic digestion followed by two dimensional thin layer chromatography to separate the various polypeptide fragments. We shall isolate the fragment containing the go24- alteration. The amino acid sequence of this fragment will then be determined. In this way we should gain information about the mechanisms controlling the processing of capsid proteins during viral assembly. In earlier work we have shown that viral capsids are first assembled and then filled with DNA. Currently, we are investigating the mechanisms by which T4 DNA is packaged into preformed viral capsids. For these studies, we have constructed a series of temperature dependent double mutants. Temperature shift experiments with these double mutants will be carried out to determine which viral functions are required for head filling.